# File lib/phusion_passenger/utils.rb, line 194
        def prepare_app_process(startup_file, options)
                options["app_root"] = canonicalize_path(options["app_root"])
                Dir.chdir(options["app_root"])
                
                lower_privilege(startup_file, options)
                path, is_parent = check_directory_tree_permissions(options["app_root"])
                if path
                        username = Etc.getpwuid(Process.euid).name
                        groupname = Etc.getgrgid(Process.egid).name
                        message = "This application process is currently running as " +
                                "user '#{username}' and group '#{groupname}' and must be " +
                                "able to access its application root directory " +
                                "'#{options["app_root"]}'. "
                        if is_parent
                                message << "However the parent directory '#{path}' " +
                                        "has wrong permissions, thereby preventing " +
                                        "this process from accessing its application " +
                                        "root directory. Please fix the permissions " +
                                        "of the directory '#{path}' first."
                        else
                                message << "However this directory is not accessible " +
                                        "because it has wrong permissions. Please fix " +
                                        "these permissions first."
                        end
                        raise(message)
                end
                
                ENV["RAILS_ENV"] = ENV["RACK_ENV"] = options["environment"]
                
                base_uri = options["base_uri"]
                if base_uri && !base_uri.empty? && base_uri != "/"
                        ENV["RAILS_RELATIVE_URL_ROOT"] = base_uri
                        ENV["RACK_BASE_URI"] = base_uri
                end
                
                encoded_environment_variables = options["environment_variables"]
                if encoded_environment_variables
                        env_vars_string = encoded_environment_variables.unpack("m").first
                        env_vars_array  = env_vars_string.split("\0", -1)
                        env_vars_array.pop
                        env_vars = Hash[*env_vars_array]
                        env_vars.each_pair do |key, value|
                                ENV[key] = value
                        end
                end
                
                # Instantiate the analytics logger if requested. Can be nil.
                require 'phusion_passenger/analytics_logger'
                options["analytics_logger"] = AnalyticsLogger.new_from_options(options)
                
                # Make sure RubyGems uses any new environment variable values
                # that have been set now (e.g. $HOME, $GEM_HOME, etc) and that
                # it is able to detect newly installed gems.
                Gem.clear_paths
                
                # Because spawned app processes exit using #exit!, #at_exit
                # blocks aren't called. Here we ninja patch Kernel so that
                # we can call #at_exit blocks during app process shutdown.
                class << Kernel
                        def passenger_call_at_exit_blocks
                                @passenger_at_exit_blocks ||= []
                                @passenger_at_exit_blocks.reverse_each do |block|
                                        block.call
                                end
                        end
                        
                        def passenger_at_exit(&block)
                                @passenger_at_exit_blocks ||= []
                                @passenger_at_exit_blocks << block
                                return block
                        end
                end
                Kernel.class_eval do
                        def at_exit(&block)
                                return Kernel.passenger_at_exit(&block)
                        end
                end
                
                
                # Rack::ApplicationSpawner depends on the 'rack' library, but the app
                # might want us to use a bundled version instead of a
                # gem/apt-get/yum/whatever-installed version. Therefore we must setup
                # the correct load paths before requiring 'rack'.
                #
                # The most popular tool for bundling dependencies is Bundler. Bundler
                # works as follows:
                # - If the bundle is locked then a file .bundle/environment.rb exists
                #   which will setup the load paths.
                # - If the bundle is not locked then the load paths must be set up by
                #   calling Bundler.setup.
                # - Rails 3's boot.rb automatically loads .bundle/environment.rb or
                #   calls Bundler.setup if that's not available.
                # - Other Rack apps might not have a boot.rb but we still want to setup
                #   Bundler.
                # - Some Rails 2 apps might have explicitly added Bundler support.
                #   These apps call Bundler.setup in their preinitializer.rb.
                #
                # So the strategy is as follows:
                
                # Our strategy might be completely unsuitable for the app or the
                # developer is using something other than Bundler, so we let the user
                # manually specify a load path setup file.
                if options["load_path_setup_file"]
                        require File.expand_path(options["load_path_setup_file"])
                
                # The app developer may also override our strategy with this magic file.
                elsif File.exist?('config/setup_load_paths.rb')
                        require File.expand_path('config/setup_load_paths')
                
                # If the Bundler lock environment file exists then load that. If it
                # exists then there's a 99.9% chance that loading it is the correct
                # thing to do.
                elsif File.exist?('.bundle/environment.rb')
                        require File.expand_path('.bundle/environment')
                
                # If the Bundler environment file doesn't exist then there are two
                # possibilities:
                # 1. Bundler is not used, in which case we don't have to do anything.
                # 2. Bundler *is* used, but the gems are not locked and we're supposed
                #    to call Bundler.setup.
                #
                # The existence of Gemfile indicates whether (2) is true:
                elsif File.exist?('Gemfile')
                        # In case of Rails 3, config/boot.rb already calls Bundler.setup.
                        # However older versions of Rails may not so loading boot.rb might
                        # not be the correct thing to do. To be on the safe side we
                        # call Bundler.setup ourselves; calling Bundler.setup twice is
                        # harmless. If this isn't the correct thing to do after all then
                        # there's always the load_path_setup_file option and
                        # setup_load_paths.rb.
                        require 'rubygems'
                        require 'bundler'
                        Bundler.setup
                end
                
                # Bundler might remove Phusion Passenger from the load path in its zealous
                # attempt to un-require RubyGems, so here we put Phusion Passenger back
                # into the load path. This must be done before loading the app's startup
                # file because the app might require() Phusion Passenger files.
                if !$LOAD_PATH.include?(LIBDIR)
                        $LOAD_PATH.unshift(LIBDIR)
                        $LOAD_PATH.uniq!
                end
                
                
                # !!! NOTE !!!
                # If the app is using Bundler then any dependencies required past this
                # point must be specified in the Gemfile. Like ruby-debug if debugging is on...
                
                PhusionPassenger._spawn_options = options
        end